Journal of Plankton Research Vol.23 no.10 pp.1147-1155, 2001
© Oxford University Press 2001
The intermediate disturbance hypothesis—species diversity or functional diversity?
1 Institute Of Freshwater Ecology And Inland Fisheries, Department Of Limnology Of Lowland Rivers And Shallow Lakes, Müggelseedamm 301, D-12 587 Berlin, Germany, 2 University Of Potsdam, Institute For Biochemistry And Biology, Maulbeerallee 2,d-14469 Potsdam, Germany
Corresponding Author: Guntram WeithofF. E-Mail: WEITHOFF{at}RZ.UNI-POTSDAM.DE
Phytoplankton dynamics in a shallow eutrophic lake were investigated over a 3-year period with respect to environmental forces which drive species composition and diversity. Diversity was calculated on the basis of species as well as on the basis of their functional properties (the C-R-S concept). Stratification and water column mixing had a strong impact on phytoplankton composition. Application of a similarity–diversity model revealed that a high diversity was a transient non-stable state, whereas drastic changes or long-lasting stable environmental conditions are characterized by low diversity. This effect was more pronounced when the diversity was calculated on the basis of the phytoplankton species' functional properties. Thus, this functional approach supports the intermediate disturbance hypothesis from field data.